Synthesis and evaluation of multitarget new 2-aminothiazole derivatives as potential anti-Alzheimer's agents.

In this study, two diverse series of 2-aminothiazole-based multitarget compounds, one propenamide and the other propanamide derivatives, were designed and synthesized. Subsequently, their anticholinesterease and antioxidant (ORAC) activities were tested. Among them, compound 3e was the most potent acetylcholinesterase (AChE) inhibitor (AChE IC50 = 0.5 µM, butyrylcholinesterase [BChE] IC50 = 14.7 µM) and compound 9e was the most potent BChE inhibitor (AChE IC50 = 3.13 µM, BChE IC50 = 0.9 µM). Kinetic experiments showed that both compounds were mixed-type inhibitors. According to the anticholinesterease activity results, five compounds (3e, 4e, 5e, 9d, and 9e) were selected for further activity studies, all of which are dual cholinesterase inhibitors. Then, selected compounds were investigated in terms of their metal chelation activity. Moreover, their neuroprotective effects against H2 O2 -induced damage in the PC12 cell line were evaluated at 10 µM and the results showed that the neuroprotective effect of 3e was 53% compared with the reference ferulic acid (77%). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) results of selected compounds revealed that the compounds were noncytotoxic. Additionally, 3e was more effective in reducing lipopolysaccharides-induced interleukin-1ß (IL-1ß), IL-6, tumor necrosis factor-α (TNF-α), and nitric oxide (NO) production in the human monocyte derived from patient with acute monocytic leukemia cell line compared with other selected compounds. Finally, a molecular docking study was also performed.

New thiourea and benzamide derivatives of 2-aminothiazole as multi-target agents against Alzheimer's disease: Design, synthesis, and biological evaluation.

In this study, two series of compounds were designed and synthesized, bearing thiourea and benzamide derivatives at position 2 of 4-subtituted-2-aminothiazole, respectively. Then, the inhibition potency of all final compounds for cholinesterase enzymes were evaluated. Among the thiourea derivatives, 3c (IC50 = 0.33 µM) was identified as the most potent and selective butyrylcholinesterase inhibitor. Additionally, benzamide derivative 10e (AChE IC50 = 1.47 and BChE IC50 = 11.40 µM) was found as a dual cholinesterase inhibitor. The type of inhibition for both compounds was determined by kinetic studies and the results showed that the compounds were mixed type inhibitors. Moreover, all title compounds were investigated in terms of their antioxidant (DPHH, ORAC) and metal chelator activities. In addition, the neuroprotective effects of selected compounds (3c, 3e, 6c, 6e and 10e) against H2O2-induced damage in the PC12 cell line were tested. The experimental findings demonstrated that thiourea-derived 6e (40.4 %) and benzamide-derived 10e (37.8 %) have a neuroprotective effect of about half as ferulic acid at 10 µM. Subsequently, the cytotoxicity of selected compounds was examined by the MTT assay, and the compounds were found not to have cytotoxic effect on the PC12 cell line in 24 h. Additionally, compounds 6e and 10e were also found to be more effective in inhibiting the release of IL-1ß, IL-6, TNF-α and NO compared to other selected compounds in this study.